Preparation Of Waterborne Polyurethane Coatings Modified By Guanidinated Chitosan

Antibacterial coatings are rapidly emerging as a primary component of the resistance to bacterial pathogens.Due to the development of materials science and biotechnology,people hope to explore more antibacterial surfaces.Comparing with the traditional solvent based PU coatings,environmentally friendly waterborne polyurethane?WPU?coatings are used more extensively due to their low VOCs emission.Chitosan is recommended as a functional material,and this natural polymer has excellent properties such as biocompatibility,biodegradability,non-toxicity,and adsorption properties.Currently,many efforts have been devoted to modify PU with natural CS for the preparation of new biomaterials with excellent mechanical property,good biocompatibility and so on.However,chitosan exhibited solubility in the acid solution or with the low molecular weight,and this poor solubility limited the application in.Guanidinium salts,as one of the important guanidine compounds,can be synthesized to many kinds of guanidine derivatives.These derivatives give strong alkalinity,good characteristics of water-soluble,high stability and good anti-bacterial property and can be used as antibacterial agents in many fields.The addition of GCS to waterborne polyurethane can improve the antibacterial properties of coatings,and it has potential applications in the fields of medical antibacterial,architectural decoration and public places.The main research contents as follows:?1?Isophorone diisocyanate?IPDI?and polytetra-methylene-ether-glycol?PTMG?as the main raw material,with N-methyl diethanolamine?MDEA?as cationic hydrophilic chain extender,cationic waterborne polyurethane was prepared?CWPU?.We discussed the qualities of MDEA effect on the extrinsic feature,stability,particle size distribution,viscosity of CWPU emulsions and water absorption rate of the film by some advanced characterization method including FTIR,¹H-NMR,¹³C-NMR,UV spectra and so on.Meanwhile,we analyzed the thermal stability of the latex film by TG and DTG.With comprehensive consideration,we selected w?MDEA?=7.5%and R=1.3 as the optimized experimental parameters to carry out the further experiments.?2?In order to improve the solubility and antibacterial property of chitosan,we produced the guanidinylated chitosan by chemical modification.FTIR and ¹³C-NMR indicated that the guanidinylated chitosan was synthesized successfully and substitution degree can up to 44%.?3?The waterborne polyurethane was modified by adding different CS content and different GCS content,and the appearance,Infrared Spectrum FTIR,Thermogravimetric Analysis,tensile properties,surface topography and antibacterial property of blending films were researched systematically.The results show that the additive of both GCS and CS can improve the thermal stability of waterborne polyurethane.The tensile strength is increasing while the breaking elongation is decreasing.As far as antibacterial activity are concerned,the inhibition zone showed that the inhibitive effect of staphylococcus aureus is more obvious than escherichia coli,and with the increase of the GCS or CS content,the antibacterial effect was enhanced.As expected,the antimicrobial activity of GCS/CWPU blending films were superior to CS/CWPU films.